Systems are commercially available which are used in the production of polyurethane shoe soles. In general, these systems comprise a polyether diol, a polyether triol, a chain extender (such as 1,4-butanediol or ethylene glycol), blowing agent, catalyst and surfactant. When mixed with an isocyanate, these systems yield polyurethane products which have met with some commercial success. The amounts of triol and chain extender are generally chosen to give the best balance of green strength and low temperature flex-fatigue resistance. Although the systems have met with some success, they do suffer certain disadvantages. Specifically, it is possible to increase the low temperature flex-fatigue resistance, but the green strength of the product upon removal from the mold will then suffer. Similarly, it is possible to enhance the green strength, but the low temperature flex-fatigue resistance will suffer. Finally, known systems can only be used over relatively narrow isocyanate indices (e.g., from 98 to 100).
Dispersions of polyureas and/or polyhydrazodicarbonamides in organic compounds containing at least one hydroxyl group are known and are used extensively in the flexible foam area (see, e.g., U.S. Pat. Nos. 3,325,421; 4,042,537; 4,089,835; 4,293,470; 4,296,213; and 4,374,209).